Conventionally, intermediate injection is sometimes utilized for the purpose of improving the efficiency of a compressor used in refrigeration equipment, and an injection passage is sometimes formed in a housing member of a compressor such as a fixed scroll member in order to bring injected refrigerant to a compression chamber of the compressor. In the intermediate injection, refrigerant is injected into the compression chamber at a pressure (an intermediate pressure) between the low pressure in the refrigerating cycle and the high pressure in the refrigerating cycle.
When performing intermediate injection, there is a case that the pressure in the compression chamber into which refrigerant is to be injected becomes higher than the pressure of the injected refrigerant, and the refrigerant flows backward from the compression chamber to the side of the injection pipe. The space outside the compression chamber in which refrigerant may flow backward is a space that does not contribute to compression of the refrigerant, and the volume of this space is called “dead volume” (a volume that does not function as a compression chamber)). It is desirable that the dead volume is as small as possible, and therefore a check valve to prevent backflow of the refrigerant is sometimes arranged close to the compression chamber in the injection passage formed in the housing member.
For example, Japanese Laid-open Patent Publication No. H11-107950 discloses a compressor in which a check valve chamber, in which a cylindrical valve body moves, is arranged in an injection passage formed in a fixed scroll member. Cutouts are formed in the valve body, on an outer peripheral face being in sliding contact with an inner peripheral face of the check valve chamber, and on an end face on the side of an injection port connected to a compression chamber. Injected refrigerant passes through a fluid. passage having a passage between the outer periphery face of the valve body and the inner peripheral face of the check valve chamber (that is, the cutout portion formed in the outer peripheral face of the valve body) and a passage between the end face on the injection port side of the valve body and the opposing face abutting the end face (that is, the cutout portion formed in the end face of the valve body), and then is supplied to the compression chamber.